The invention relates to a method of producing a compression mould profile of a compression mould for a non-circular, sintered chain wheel or cog belt wheel based on the features defined in independent claim 1 as well as a method of producing a non-circular chain wheel or a non-circular cog belt wheel from powdered metal.
In drive systems, there are applications in which non-circular chain wheels or cog belt wheels are used with a view to producing specific effects. One such application is known from patent specification WO 03/046413 A1, for example, which discloses a synchronous drive comprising an endlessly circulating tensioning means and at least two rotary elements which engage with the tensioning means. In this instance, a fluctuating load torque acting on the second rotary element is largely compensated due to a non-circular design of the first rotary element, which transmits an opposing fluctuating drive torque of approximately the same magnitude via the tensioning means to the second rotary element. Such an arrangement may be used with a camshaft drive for example, as a means of reducing torsional oscillation of the driven camshaft as well as vibrations of the tensioning means.
Whereas sintering is commonly used to produce circular cog belt wheels or chain wheels in large batches by powder metallurgy, sintering methods have not been widely used to produce non-circular chain wheels or cog belt wheels to date because the fact that the finished component is non-circular means that the design of the mould used to make a chain wheel or a cog belt wheel by sintering using conventional methods is not satisfactory. In order to produce sintered components requiring no finishing process involving the removal of material to accurate dimensions, it is often necessary for them to be finished by a calibration process, in which case the compression mould used to produce the compact of powdered metal and the calibrating mould for calibrating the sintered component must be adapted to one another, which poses additional requirements with regard to the design of a compression mould. In particular, the design of the compression mould and its cross-sectional profile has a major influence on the result of the process used to produce sintered workpieces.